The present disclosure relates to systems and methods for treating wastewater and effluent such as water that has been used in conjunction with subterranean operations.
Various types of subterranean well bore operations (e.g., fracturing, drilling, etc.) sometimes generate large volumes of wastewater or effluent, such as produced water, surface water, flowback water, and the like. Typically, this wastewater or effluent is collected into various ponds, sumps, or tanks at a job site and eventually transferred to a main holding area or sump. From here, the water may be transferred to a water treatment plant for processing before discharge to the environment. Wastewater and effluent may contain a variety of components. The wastewater or effluent often includes a dilute slurry of finely divided particulates or other undissolved solids, either indigenous to the subterranean formation or mine site or a by-product of a mining or well treatment operation. Wastewater or effluent also may be produced by other processes and/or equipment at a job site, including but not limited to rainwater and deck drainage, as well as water used as a coolant, washdown or cleaning fluid, storm water, and/or other surface operations.
Moreover, certain drilling fluids may include invert emulsion fluids, i.e., emulsions in which the non-oleaginous fluid is the discontinuous phase and the oleaginous fluid is the continuous phase. During the drilling process, it is not uncommon for such invert emulsion drilling fluids to encounter a water bearing formation, which may alter the ratio of oleaginous fluid to non-oleaginous fluid. In some cases, emulsions that are difficult to break may form in the fluid. The recovered drilling fluid also may include other waste materials such as oils and/or particulate materials suspended therein. Many offshore rigs drilling with oil-based drilling fluids may produce significant amounts of wastewater or effluent that includes oil, dissolved and undissolved salts, coarse and fine undissolved solids in this way. Conventional emulsion breaker additives sometimes may be used to treat such fluids and restore the desired ratios. The wastewater or effluent usually may not be directly discharged into the sea because of its hydrocarbon content, which is usually higher than regulatory limits. Therefore, wastewater or effluent is often transported in boat tanks to shore for disposal according to the local regulations, or treated to remove contaminants before the remaining clean water is either discharged or reused. The transportation of contaminants and/or untreated wastewater or effluent can be costly and/or increase the operational complexity of offshore drilling operations.
While embodiments of this disclosure have been depicted, such embodiments do not imply a limitation on the disclosure, and no such limitation should be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.